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HL: Fachverband Halbleiterphysik

HL 44: Nitrides: Preparation and characterization II

HL 44.7: Vortrag

Donnerstag, 21. März 2024, 15:45–16:00, EW 015

Highly spatially resolved investigation of structural and optical properties of a GaN-based p-n-diode — •Luca Greczmiel, F. Bertram, G. Schmidt, P. Veit, H. Eisele, A. Dempewolf, S. Petzold, J. Christen, A. Strittmatter, and A. Dadgar — Otto-von-Guericke-University Magdeburg, Magdeburg, Germany

GaN based devices are promising candidates for the next generation of high power electronics due to its high breakdown voltage, high electron mobility and highthermal conductivity. To understand the physics of these complex devices, the fundamental structural, electronic and material properties have to be investigated. In this study, we investigated a GaN based p-n-structure by cathodoluminescence microscopy (CL) directly performed in a scanning transmission electron microscope (STEM). The diode was grown by metal organic vapor phase epitaxy on top of an optimized template. An n-doped GaN layer with nominal 8x10¹⁸ cm⁻³ Si doping serves as current spreading layer. The p-n-junction is formed by a 970 nm thick GaN:Si layer and a 280 nm GaN:Mg layer with nominal doping concentration of 7x10¹⁷ cm⁻³ and 1-3x10¹⁹ cm⁻³, respectively. In scanning electron micrsocopy images, we were able to determine the thickness of the GaN:Mg layer to 280 nm due to the distinct doping contrast. In STEM-CL linescans, we observe a drastic change of the recombination channels. The donor bound exciton emission is dominant at 357.2 nm in the n-GaN layer. Towards the p-n-junction, donor-acceptor-pair recombination (DAP) increases mono-exponentially in intensity and reaches its maximum at the p-n-interface.

Keywords: cathodoluminescence; scanning transmission electron microscope; GaN; diode; doping